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Scientists in the United States examined the use of different conductive fillers in a lithium-ion battery electrode, finding that adding single-walled carbon nanotubes to a nickel-cobalt-manganese cathode resulted in to improved electrical conductivity and increased speed capability for the overall battery. The findings, according to the group, could provide new insight into the design of electrodes for high-power, high-energy batteries.
From pv magazine Global.
Among the many avenues to improve today’s energy storage technologies, adding conductive “filler” materials to electrodes promises improved speed, conductivity and overall battery performance capability.
“Although a variety of conductive fillers have been extensively developed,” explain scientists led by the University of Texas at Austin (UTA), “understanding how the geometry and dimensionality of these fillers affect the conductivity of the electrode, the architecture and, ultimately, the electrochemical performance in high energy storage systems is still insufficient. “
The team experimented with three different conductive carbon materials to determine which one offered the best performance. Variable amounts of single-walled carbon nanotubes, graphene nanosheets and “Super P”, a type of carbon black particle already commonly used as a conductive filler in batteries, have been added to a nickel-cobalt-manganese (NCM) cathode. lithium ion.
These cathodes were then measured using various spectroscopic and electrochemical characterization techniques. Full results are published in Unveiling the dimensionality effect of conductive fillers in thick battery electrodes for high-energy storage systems, Posted in Applied Physics Reviews.
Carbon nanotubes
Single-walled carbon nanotubes (SWCNTs) have proven to be the best performing additive. The team observed that the nanotubes formed a conductive coating around the NCM particles and also formed interconnected networks between the NCM particles. Graphene nanosheets had a similar effect but formed less uniform structures.
The best of the SWCNT electrodes showed a capacity of 142 milliampere per gram (mAh / g) at a charge rate of 0.2 C, dropping to 101 mAh / g when the rate increased to 2 C. The group also found that since 0.16% by weight of SWCNT was sufficient to ensure good conductivity. “When an electrically conductive filler is added to an insulating matrix,” explains UTA’s Guihua Yu, “there will be significant increases in conductivity once the first conductive path through the composite is formed.”
The group says its findings suggest that integrating SWCNT in this way could facilitate better ion and charge transfers, leading to better-performing batteries especially at high discharge rates. And overall, better understanding of the behavior of conductive fillers could open new doors in the design of high energy / power density electrodes.
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